"The five gold rings are a win–win whatever interpretation is applied. Gold prices have risen from £15.64 an ounce on 1 December 1970 to £1,060.95 an ounce on 1 December 2012.

"But the gold rings in the verse have also been interpreted as a variation of "five goldspinks", with a goldspink being an old name for a goldfinch.

"Since the Victorians stopped trapping goldfinches, which almost led to their disappearance in parts of England, especially in the north, they have done well. Numbers have increased by 124% since 1970, when the first detailed monitoring occurred, and since 1995 they have almost doubled, according to the RSPB."